Selection of rat - proof optical cable
Whether it is the suspension line of overhead optical cable in forest area, the human (hand) hole of pipeline optical cable, or the groove of laying optical cable along high-speed and high-speed railway, the laying channel of optical cable is often the place where squirrels or rats like to activity. Rats have the habit of grinding their teeth. With the increase of optical cable laying, it is more and more common for rats to bite the optical fiber in the optical cable. In order to prevent the damage of mice to optical cables, optical cables specially used to prevent rodent biting (hereinafter referred to as rat optical cables) have been gradually applied in engineering.
Protection method of rat optical cable
There are three main ways to protect mouse optical cable:
The first is chemical stimulation method. It is to add a kind of spicy agent in the sheath of optical cable. When mice bite the sheath of optical cable, the spicy agent can make the oral mucosa and taste nerve of mice be strongly stimulated, and make mice give up biting. The chemical properties of the spicy agent are relatively stable, but when the optical cable is used in the long-term outdoor environment, the spicy agent will gradually lose from the sheath due to water solubility and other factors, which is difficult to ensure the long-term anti-rat effect of the optical cable.
The second method is physical stimulation. It is to add a layer of glass yarn or FRP (Fiber Reinforced Plastics) composed of glass fiber between the inner sheath and the outer sheath of the optical cable. Because the glass fiber is extremely fine and brittle, in the process of rodent biting, the crushed glass residue will hurt the mouse's mouth, making them afraid of the cable. The physical stimulation method has a good anti-rat effect, but the manufacturing cost of optical cable is high, and the glass fiber during the construction of optical cable is also easy to hurt the construction personnel. Because it does not contain metal components, optical cables can be used in strong electromagnetic environments.
The third is armor protection method. It is to set a hard metal reinforcement layer or armor layer (hereinafter referred to as armor layer) outside the cable core, so that it is difficult for rats to chew through the armor layer, so as to achieve the purpose of protecting the cable core. Metal armor is the conventional manufacturing process of optical cable. The manufacturing cost of optical cable with armor protection method is not much different from that of ordinary optical cable. Therefore, the current anti-rat optical cable mainly adopts armor protection method.
Main types of common anti-mouse optical cable
According to the different armoring materials, the commonly used anti-rat optical cable is mainly divided into two types: stainless steel armored optical cable and thin round steel wire armored optical cable.
Stainless steel armored optical cable
Laboratory tests show that the conventional GYTS cable has a good ability to prevent mice (house mice), but when the cable is laid in the field, the exposed steel belt will gradually corroded after mice bite, and the lap of the steel belt will be easy for mice to further bite. Therefore, the anti-rat ability of ordinary steel tape armored optical cable is very limited.
Stainless steel belt has good corrosion resistance and higher hardness than ordinary steel belt. At present, 304 stainless steel belt armor is used for the anti-rat optical cable collected by an operator. The optical cable adopts the structure of buried optical cable, and the cable model is GYTA43.
Although GYTA43 optical cable has a good anti-rat effect in practical application, it also has the following two problems.
(1) The main protective effect on rat bite is stainless steel belt, aluminum + polyethylene inner protective layer has no effect on rat bite prevention; The outer diameter and weight of optical cable are large, which is not conducive to laying, and the price of optical cable is also higher.
(2) The position of the cable stainless steel belt lap is conducive to rodent biting, and the long-term effectiveness of protection still needs time to test.
Fine wire armored optical cable
The anti-penetration ability of steel belt armored optical cable is related to the thickness of steel belt, as shown in Table 1.
Table 1 Anti-penetration of steel strips with different thicknesses
Flat steel strip thickness (mm) | Penetration resistance (N, note) |
0.13 | 59 |
0.15 | 76 |
0.18 | 95 |
0.2 | 120 |
Note: The anti-penetration of wrinkled steel strip is better than that of flat steel strip |
The increase of the thickness of the steel strip will make the bending performance of the fiber optic cable worse, so the thickness of the armored steel strip in the fiber optic cable is usually 0.15mm ~ 0.20mm. The armor layer of the steel wire armored cable uses a thin round steel wire with a diameter of 0.45mm ~ 1.6mm. The diameter of the steel wire is several times the thickness of the steel belt, which greatly improves the anti-mouse biting performance of the cable, and the cable still has good bending performance.
When the cable core size is constant, the outer diameter of steel wire armored fiber optic cable is larger than that of steel tape armored fiber optic cable, resulting in high self-weight and high cost. In order to reduce the outer diameter of steel wire armored fiber optic cable, the core of steel wire armored rat resistant fiber optic cable usually adopts a central tube structure.
When the core number of the wire armored anti-rat optical fiber cable is greater than 48 cores, in order to facilitate the core management, multiple microbeam tubes are set in the loose sleeve tube, and each microbeam tube is separately loaded with 12 cores or 24 cores to become an optical fiber bundle.
Due to the small size of the cable core and poor mechanical properties of the steel wire armored anti-mouse cable, in order to prevent the deformation of the cable, steel tape will be armored outside the wrapped steel wire to ensure the shape of the cable. In addition, the steel belt also further enhances the anti-mouse performance of the fiber optic cable.
The type name of steel wire armored rat proof optical fiber cable is not uniform. Most manufacturers name the central tube optical fiber cable GYXTS, but this name does not reflect the structure of steel wire armor. Some manufacturers name the cable GYQXT3S.
Although there are many types of mouse cable, the most widely used is GYTA43 and GYXTS mentioned above. From the structure of the cable, GYXTS may have a better long-term anti-rat effect, and the anti-rat effect has also been tested for nearly 10 years. GYTA43 cable has not been used for a long time in the project, and the long-term anti-rat effect remains to be tested.
With the same number of fiber cores, the outer diameter and weight of GYXTS cable are almost the same as that of ordinary GYTS cable, while GYTA43 is much higher, as shown in Table 2.
Table 2 Reference values of outer diameter and weight of different optical cables
Optical cable type
| Core number | external diameter (mm) | Weight (kg / km) |
GYTS | 48 | 10.8 | 111 |
GYTA43 | 48 | 15.0 | 220 |
GYXTS | 48 | 10.2 | 120 |
At present, there is only one kind of anti-rat cable collected by an operator, GYTA43. However, from the above analysis, it can be seen that GYXTS anti-rat cable may be slightly better than GYXTS in terms of anti-rat performance, convenience of construction, and price of optical cable.
